#define _CRT_SECURE_NO_WARNINGS 1
#include<iostream>
using namespace std;
int main()
{
    int n; 
    double Sn=0;
    cin >> n;
    for (int i = 1; i <= n; i++)
    {
        
        Sn += 1 / i;
    }
    printf("%f", Sn);
    return 0;
}